* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
    color: #333;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 20px;
}

header {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 20px;
    margin-bottom: 20px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
}

header h1 {
    text-align: center;
    color: #4a5568;
    margin-bottom: 20px;
    font-size: 2.5em;
    font-weight: 700;
}

nav {
    display: flex;
    justify-content: center;
    gap: 15px;
    flex-wrap: wrap;
}

.nav-btn {
    padding: 12px 24px;
    border: none;
    border-radius: 25px;
    background: #e2e8f0;
    color: #4a5568;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.nav-btn:hover {
    background: #cbd5e0;
    transform: translateY(-2px);
}

.nav-btn.active {
    background: #4299e1;
    color: white;
    box-shadow: 0 6px 20px rgba(66, 153, 225, 0.4);
}

main {
    background: rgba(255, 255, 255, 0.95);
    border-radius: 15px;
    padding: 30px;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.1);
    backdrop-filter: blur(10px);
    min-height: 500px;
}

.section {
    display: none;
}

.section.active {
    display: block;
}

/* 模拟考试样式 */
.exam-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 30px;
    padding-bottom: 15px;
    border-bottom: 2px solid #e2e8f0;
}

.exam-header h2 {
    color: #2d3748;
    font-size: 2em;
}

.exam-info {
    display: flex;
    gap: 30px;
    font-size: 16px;
    color: #4a5568;
}

.exam-info span {
    font-weight: 600;
}

.question-container {
    max-width: 800px;
    margin: 0 auto;
}

.question-content {
    background: #f7fafc;
    padding: 25px;
    border-radius: 12px;
    margin-bottom: 25px;
    border-left: 5px solid #4299e1;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.question-content p {
    font-size: 18px;
    line-height: 1.6;
    color: #2d3748;
}

.options-container {
    margin-bottom: 30px;
}

.option-item {
    background: white;
    padding: 15px 20px;
    margin-bottom: 12px;
    border-radius: 10px;
    border: 2px solid #e2e8f0;
    cursor: pointer;
    transition: all 0.3s ease;
    display: flex;
    align-items: center;
    gap: 15px;
}

.option-item:hover {
    border-color: #4299e1;
    transform: translateX(5px);
}

.option-item.selected {
    border-color: #4299e1;
    background: #ebf8ff;
}

.option-item input[type="checkbox"],
.option-item input[type="radio"] {
    width: 20px;
    height: 20px;
    cursor: pointer;
}

.option-label {
    font-size: 16px;
    color: #4a5568;
    flex: 1;
}

.navigation-buttons {
    display: flex;
    justify-content: space-between;
    gap: 15px;
}

.nav-button, .submit-button, .training-button, .import-button {
    padding: 12px 30px;
    border: none;
    border-radius: 25px;
    font-size: 16px;
    font-weight: 600;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.1);
}

.nav-button {
    background: #e2e8f0;
    color: #4a5568;
}

.nav-button:hover {
    background: #cbd5e0;
    transform: translateY(-2px);
}

.submit-button {
    background: #48bb78;
    color: white;
}

.submit-button:hover {
    background: #38a169;
    transform: translateY(-2px);
}

.training-button {
    background: #ed8936;
    color: white;
}

.training-button:hover {
    background: #dd6b20;
    transform: translateY(-2px);
}

.import-button {
    background: #4299e1;
    color: white;
}

.import-button:hover {
    background: #3182ce;
    transform: translateY(-2px);
}

/* 错题库样式 */
.questions-list {
    max-height: 500px;
    overflow-y: auto;
}

.wrong-question-item {
    background: white;
    padding: 20px;
    margin-bottom: 15px;
    border-radius: 10px;
    border-left: 5px solid #e53e3e;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.05);
}

.wrong-question-item h4 {
    color: #2d3748;
    margin-bottom: 10px;
    font-size: 18px;
}

.wrong-question-options {
    margin: 10px 0;
}

.wrong-option {
    padding: 8px 12px;
    margin: 5px 0;
    border-radius: 6px;
    font-size: 14px;
}

.wrong-option.correct {
    background: #c6f6d5;
    color: #22543d;
    border: 1px solid #9ae6b4;
}

.wrong-option.incorrect {
    background: #fed7d7;
    color: #742a2a;
    border: 1px solid #feb2b2;
}

.wrong-answer-info {
    margin-top: 10px;
    padding: 10px;
    background: #f7fafc;
    border-radius: 6px;
    font-size: 14px;
    color: #4a5568;
}

/* 训练界面样式 */
.training-controls {
    display: flex;
    gap: 15px;
    margin-bottom: 25px;
    justify-content: center;
}

.training-container {
    max-width: 800px;
    margin: 0 auto;
}

/* 导入界面样式 */
.import-container {
    max-width: 800px;
    margin: 0 auto;
}

.file-upload {
    margin-bottom: 25px;
    text-align: center;
}

.file-upload input[type="file"] {
    display: none;
}

.upload-label {
    display: inline-block;
    padding: 15px 30px;
    background: #4299e1;
    color: white;
    border-radius: 25px;
    cursor: pointer;
    font-weight: 600;
    transition: all 0.3s ease;
    box-shadow: 0 4px 15px rgba(66, 153, 225, 0.3);
}

.upload-label:hover {
    background: #3182ce;
    transform: translateY(-2px);
}

.file-preview {
    margin-bottom: 25px;
}

.file-preview h3 {
    margin-bottom: 15px;
    color: #2d3748;
}

#filePreview {
    width: 100%;
    height: 200px;
    padding: 15px;
    border: 2px solid #e2e8f0;
    border-radius: 10px;
    resize: vertical;
    font-family: 'Courier New', monospace;
    font-size: 14px;
    background: #f7fafc;
}

.import-result {
    margin-top: 20px;
    padding: 15px;
    border-radius: 10px;
    text-align: center;
    font-weight: 600;
}

.import-result.success {
    background: #c6f6d5;
    color: #22543d;
    border: 1px solid #9ae6b4;
}

.import-result.error {
    background: #fed7d7;
    color: #742a2a;
    border: 1px solid #feb2b2;
}

/* 响应式设计 */
@media (max-width: 768px) {
    .container {
        padding: 10px;
    }
    
    header h1 {
        font-size: 2em;
    }
    
    nav {
        flex-direction: column;
        align-items: center;
    }
    
    .nav-btn {
        width: 100%;
        max-width: 200px;
    }
    
    .exam-header {
        flex-direction: column;
        gap: 15px;
        text-align: center;
    }
    
    .exam-info {
        flex-direction: column;
        gap: 10px;
    }
    
    .navigation-buttons {
        flex-direction: column;
    }
    
    .training-controls {
        flex-direction: column;
        align-items: center;
    }
    
    .training-button, .import-button {
        width: 100%;
        max-width: 200px;
    }
}

/* 动画效果 */
@keyframes fadeIn {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

.section.active {
    animation: fadeIn 0.5s ease-out;
}

/* 滚动条样式 */
.questions-list::-webkit-scrollbar {
    width: 8px;
}

.questions-list::-webkit-scrollbar-track {
    background: #f1f1f1;
    border-radius: 4px;
}

.questions-list::-webkit-scrollbar-thumb {
    background: #c1c1c1;
    border-radius: 4px;
}

.questions-list::-webkit-scrollbar-thumb:hover {
    background: #a8a8a8;
}

/* 开始考试按钮样式 */
.start-exam-container {
    text-align: center;
    padding: 50px 20px;
}

.start-exam-button {
    padding: 20px 50px;
    font-size: 24px;
    font-weight: 700;
    background: linear-gradient(135deg, #48bb78, #38a169);
    color: white;
    border: none;
    border-radius: 50px;
    cursor: pointer;
    transition: all 0.3s ease;
    box-shadow: 0 8px 25px rgba(72, 187, 120, 0.4);
    margin-bottom: 20px;
}

.start-exam-button:hover {
    transform: translateY(-5px);
    box-shadow: 0 12px 35px rgba(72, 187, 120, 0.6);
    background: linear-gradient(135deg, #38a169, #2f855a);
}

.exam-info-text {
    font-size: 16px;
    color: #4a5568;
    max-width: 400px;
    margin: 0 auto;
    line-height: 1.5;
}
